The Method for Treating Fine Slime in Flotation Process
In flotation production process, in order to avoid the deterioration of fine slime to the flotation process and remove the harmful effects of fine slime, we often use the following measures.
①Adding dispersant to reduce its impact when the fine slime is not too much
Generally sodium silicate and sodium hexametaphosphate can be added. The dispersant is a pure electrolyte whose role is to increase the electric potential of the surface of the fine slime. When the fine slime are close to each other, due to the same electrical and mutually exclusive, so that slime play the role of dispersion to prevent non-selective agglomeration of fine slime.
The method of adding dispersant is relatively simple which is suitable for less slime situation. However, this method still can not fundamentally overcome the shortcomings of poor selectivity and large consumption of dosage caused by fine slime, so we need to strengthen the concentration process in the production.
②Pre-desliming before flotation
There are two ways to do pre-desliming: flotation desliming and mechanical desliming. Flotation desliming is using small amount of foaming agent and collector to float part of the slime, then process the coarse-grained flotation. Mechanical desliming is using classifier (such as hydrocyclones) to remove part of the fine slime before flotation. The particle size of desliming is 10-20 microns. The desliming grade is mainly determined by the performance of classifying equipment. The effect of coarse-grained flotation can be improved after desliming. The main problem is fine slime is difficult to be handled, it can be discarded if there is less useful minerals, but the grade of those useful mineral in the fine slime is often similar to the raw ore, we will lose those metals if we just discard the fine slime.
③Beneficiation of slime and sand
The process requirement of separate flotation for fine slime:
a.It is appropriate to use longer time for flotation, it is reported that it will take 40-60 minutes to do flotation for those particle size is less than 10 microns.
b.High concentration pulping (pulp concentration is up to 60%-70%), low concentration flotation (generally is less than 20%).
c.Segmental dosing, increase the quantity of collector, reduce the quantity of foaming agent.
d.Large air volume, small bubbles, weaken the rising pulp flow.
During the production, it is difficult to meet the above-mentioned technological requirement of fine slime flotation, so fine slime flotation index is not so high. Although the above-method of processing fine slime is used for the production, but it did not solve the special process of fine slime flotation. According to the present research trend, there are two ways to improve the flotation speed of fine particles: one is to increase the particle size of fine slime of flotation, another one is to reduce the particle size of flotation bubbles.
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